ICP-MS Ion Trap for Transient Multi-Element Analysis
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Solution Overview
Problem
Current ICP-MS systems, particularly those using quadrupole mass filters, are inadequate for multi-element analysis of fast transient signals from ion pulses due to their scanning nature, which limits the ability to quantify multiple elements within the short duration of signals from nanoparticles or biological cells.
Innovation Solution
Incorporating an ion trap, such as a linear ion trap, into the ICP-MS system to confine and mass-selectively eject ions, allowing for the simultaneous analysis of multiple elements from transient signals by preventing ion exit and entry during a confinement period and transmitting selected ions to a detector for measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quadrupole mass filter is used in ICP-MS, then the system is robust and cost-effective, but it cannot perform multi-element analysis of fast transient signals due to its scanning nature
Solution Approach 1:
The patent replaces the mechanical scanning mechanism of the quadrupole mass filter with a static ion trap configuration. Instead of mechanically scanning through mass ranges, the system uses electric fields to confine and selectively eject ions based on their mass-to-charge ratio, enabling simultaneous multi-element detection without mechanical movement.
Solution Approach 2:
The ion trap operates using periodic radio frequency (RF) voltages applied to the trap electrodes. By modulating the RF voltage frequency and amplitude, the system periodically confines and releases ions of different masses, allowing sequential ejection of multiple elements from a single transient signal without requiring mechanical scanning.
2Measurement precision
If a scanning mass spectrometer is used, then mass resolution is achieved, but the measurement time is too long for transient signals shorter than ten milliseconds
Solution Approach 1:
The system performs preliminary ion confinement by trapping all ions from the transient signal simultaneously in the ion trap before mass analysis begins. This allows the entire ion population to be captured and stored, then sequentially analyzed at a slower pace without losing any transient signal information, effectively decoupling the fast signal acquisition from the slower mass analysis.
Solution Approach 2:
The ion trap acts as an intermediary device between the fast transient signal source and the slow scanning mass analyzer. It temporarily stores the ions and buffers the time mismatch, allowing the mass spectrometer to analyze ions sequentially at its own pace while preserving all ions from the original fast transient signal for complete multi-element analysis.
3Speed
If ions are transmitted directly to the detector, then rapid detection is possible, but mass selection cannot be achieved for multi-element analysis
Solution Approach 1:
The patent segments the ion beam by mass-to-charge ratio using the ion trap's selective ejection capability. Instead of transmitting all ions simultaneously to the detector, the system confines ions in the trap and sequentially ejects them by mass, creating separated ion streams that are then transmitted to the detector at different times, achieving both mass selection and detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables multi-element analysis of brief transient signals, improving the capability to detect and quantify elements from single particles or cells, enhancing the analytical capabilities of ICP-MS systems beyond conventional quadrupole-based systems.
Implementation Method 1
after the injecting, confining the ions of the injected ion pulse in the ion trap during a confinement period, during which the confining prevents the confined ions from exiting the ion trap and prevents other ions outside of the ion trap from entering the ion trap
Implementation Method 2
after the confinement period, ejecting ions of selected masses of the confined ions successively from the ion trap by mass-selective ejection
Implementation Method 3
ionizing a sample by ICP ionization to produce an ion pulse comprising a plurality of ions having two or more different masses
Implementation Method 4
ICP ionization
Data Source
AI summary
An inductively coupled plasma-mass spectrometry (ICP-MS) system includes an ion trap, in which ions are trapped and subsequent ejected by mass-selective ejection (MSE). The system may have a linear quadrupole configuration, in which the ion trap is a linear ion trap (LIT) that is preceded by a pre-LIT linear quadrupole device and/or a post-LIT quadrupole device. The pre-LIT and/or post-LIT quadrupole device may be configured or operated as an RF-only ion guide or as a mass filter or mass analyzer, with or without mass scanning. The system may be utilized in particular for multi-element analysis of fast transient signals produced from ion pulses, where the sample under analysis is a single particle, single biological cell, or a cloud or aerosol produced for example by single-shot laser ablation.